To significantly reduce today's severe congestion and prepare for growth expected by 2030, Arizona needs just over 3,800 new lane-miles at a total cost of $11.3 billion, in today's dollars. That's a cost of approximately $84 per resident each year. Arizona ranks ninth out 50 states and the District of Columbia in terms of most lane-miles needed and 13th in the total costs of those improvements. If the state made these improvements, it would save almost 193 million hours per year that are now wasted in traffic jams.

Arizona has two urban areas suffering from severe congestion; Phoenix-Mesa and Tucson. Phoenix is the 20th most congested region in the United States, with a Travel Time Index (TTI) of 1.35. (This means that driving times during peak traffic are 35 percent longer than during off-peak times.) And as the 26th most congested area, Tucson is close behind with a TTI of 1.31.

Unless major steps are taken to relieve congestion, drivers in these Arizona cities can expect to see TTIs of 1.64 and 1.60 by 2030, respectively. For an idea of how severe that level of congestion would be, note that this projection is worse than the traffic delays experienced today in places like Atlanta, Chicago, and San Francisco. In fact, only one cityï¿½Los Angelesï¿½currently has a TTI in excess of 1.60.

As Table 8 suggests, the picture is much better for the other Arizona cities with populations over 50,000. In these cities, the TTIs do not exceed 1.04 currently, although the relative increase in delay projected over the next 25 years for these cities is 100 percent, which will certainly be felt by local commuters. (The 'delay' in the travel time is the portion of the TTI over 1.0.) To put this into perspective, TTIs of around 1.08 reflect current traffic in cities such as Cleveland, Richmond-Petersburg, and Spokane.

Arizona can significantly reduce congestion by adding about 3,813 new lane-miles by 2030 at an estimated cost of $11.3 billion in today's dollars. This investment would save an estimated 193 million hours per year that are now lost sitting in traffic, at a yearly cost of $2.35 per delay-hour saved. This does not account for the additional benefits not quantified in this study, including: lower fuel use, reduced accident rates and vehicle operating costs, lower shipping costs and truck travel time reductions, greater freight reliability, and a number of benefits associated with greater community accessibility, including an expanded labor pool for employers and new job choices for workers.